Inertia switch



Ag 22, 1961 w. s. GILLMoR EI'AI. 2,997,557

INERTIA SWITCH Filed April e. 195e llllllll Il i] I6J 3a 25 INV T s 42 30 f 564 wILLIA I MoR Cy f WARREN D. RALEY EXTERNAL 4*;2 I BYQA CIRCUIT 56 40 10a. ITToRNEY,

Great Neck N.Y. assi ors to Gordon W. Whole New York, N.Y. gn y Filed Apr. 6, 1959, Ser. No. 804,175 6 Claims. (Cl. 20D-61.45)

This invention relates to the art of inertia switches.

A principal object of the invention is provision of an nertia switch having lan adjustable path for a magnetic olling element therein.

A further object of the invention is provision of an nertia s-witch containing an adjustable capsule containng a rolling element responsive to externally applied forces for actuating the switch.

A still `further object is provision of an inertia switch ncluding a rolling element biased to one position by a :ermanent magnet, the element being contained in an idjustably positionable capsule for determining the magniude of an external force required to displace the element 'rom said position in the capsule.

Another object is provision of an inertia switch conaining ia capsule of the character described with one or nore resilient contacts disposed to cushion the element 1nd actuate an external circuit when the element is disilaced from said one position in the capsule.

Another object is provision of an inertia switch having 1 piezoelectric contact element.

The invention employs in a preferred embodiment, a ion-magnetic casing in which is seated a permanent bar nagnet. The casing has a bore in which is adjustably xositioned a cylindrical capsule. The capsule contains a )all of magnetic material which is held at one end of the :apsule by force of magnetic attraction between the ball ind magnet. At the other end of the capsule is mounted 1n adjustable contact which may be connected to an exernal electrical circuit. The ball is displaceable from `he one end of the capsule by an externally applied force. The length of the path that the ball travels in the capsule from one end to the other is determined by the position )f the adjustable contact. The contact may be formed is a ilexible element to cushion the ball at the other end )f the capsule. The bore in the casing may be disposed ransversely to the axis of the magnet or at some angle hereto. The position of the capsule in the casing deternines the magnitude of the external force required to iisplace the ball from the position in which it is held by he magnet. Adjustable contacts may be disposed at )pposite ends of the capsule. One of the contacts may Je a piezoelectric element for producing a pulse upon mpact by the ball.

The invention will be best understood from the followng description taken together with the drawing, wherein:

FIG. 1 is an elevational view of an inertia switch emiodying the invention.

FIG. 2 is a sectional View taken on line 2-2 of HG. l.

FIG. 3 is a sectional view similar to FIG. 2 of another twitch according to the invention.

FIG. 4 is a sectional view similar to FIGS. 2 and 3 )f still another inertia switch according to the invention.

FIGS. 5 and 6 are perspective views on an enlarged .cale of contact members which may be employed in the ,witches of FIGS. 1 4.

FIG. 7 is a diagram of one mode of operation of the nvention.

FIGS. 8 and 9 are views similar to FIG. 2 of other ;witches embodying the invention.

Referring to FIGS. l and 2, there is shown a body 1) vhich may be cylindrical, rectangular, or have some )ther form as required. The -body should be made of nited States Patent 2,997,557 Patented Aug. 22, 1961 ice non-magnetic material and may be electrically conductive or non-conductive, depending upon the functions to be performed by the switch. For illustrative purposes, the body is shown in FIG. 2 as made of plastic non-conductive material.

Within the body is a bore 12 in which is xedly seated a permanent magnet 14. The magnet may be removably mounted on a plug 16 threaded in an enlarged internally threaded end 18 of the bore. The plug is slotted at 20 to facilitate removal and insertion by a screwdriver. Transverselfy disposed t0 bore 12 is another bore 22. The two bores may have their axes perpendicular at some acute angle to each other. Bore 22 is preferably threaded. Disposed in bore 22 is a hollow cylindrical non-magnetic capsule 24 formed by Ia cylindrical cup or shell 26 having a closed end 28 and an open end closed by disk-like end wall or plate 30. Plate 30 has a threaded bore in which is adjustably positioned a plug 32 serving as a contact support member. This member is toi-med of insulating material and carries electrically conductive contact members 34, 36. These contact members are spaced apart and terminate in exible, spaced bent spring fingers 38, 4Gv shown best in FIG. 5. The other straight ends of the contact members project beyond the plug 32y and provide means for connection thereto of conductors 42, 44 of an external electrical circuit, as indicated schematically in FIG. 2. Plug 32 is slotted at 33 to permit adjustment with a screwdriver.

A nut 46 is threaded on the plug 32 to secure the plug in a desired position in plate 30. The position of the plug 32 determines the length of a path between the opposite ends of the capsule in which a ball 4S is constrained to move. Ball 48 is made of ya magnetic material such as steel and is normally disposed in abutment with the closed end 28 of the capsule by the force of attraction of magnet 14 thereto. 'I'he ball is displaceable from the normal position shown in FIG. 2 by an externally applied force of acceleration or deceleration which exceeds the force of magnetic attraction holding the ball at end 28.

In order to predetermine the magnitude of the force required to displace the ball and to regulate the force with which the ball is held by the magnet the capsule is longitudinally movable in bore 22. The capsule can be fixed in a selected position by a threaded, slotted plug 50 removably abutting the closed end 28 and by a threaded sleeve 52 which surrounds member 32 and the contacts extending therefrom. The plug `50` is slotted at 51 and the sleeve 52 is provided with radial slots 54 so that they can be adjusted by means of a screwdriver or suitable wrench.

When the ball is displaced from end 28 it will continue movement due to its inertia until it reaches the dotted line position shown in FIG. 2. The spring rigers 3S, 40 serve to cushion the shock of impact of the ball and prolong the time of Contact of the ball with the iingers 38, 40.

In the form of the invention shown in FIG. 3 body 10a is indicated as for-med of metal which is electrically conductive to serve as a terminal for the external electrical circuit. The conductor 56 of the external circuit is indicated schematically as connected to the body 10a by soldering or otherwise. The capsule 24a is provided with an externally threaded cylindrical shell or cup 26a having `a closed end wall 23a slotted at 29. The magnetic ball 48 is normally held in abutment with wall 28a by the force of attraction with magnet 14. A threaded plug 30a slotted at 31 closes the open end of the tube. The threaded plug etectively secures lthe threaded shell of the capsule in the threaded bore 22. Plug 32a supports a single contact member 60 to which may be attached conductor 62 of an external electric circuit of which conductor 56 will also be a part. The flat contact member 60 extends through the insulated plug 32a and terminates in a bent spring iinger 38a angularly disposed to another bent spring finger 40a which is attached to member 60 by rivets 64, as clearly shown in FIGS. 3 and `6.

The inertia switch of FIG. 3 operates in a manner similar to that of FIG. 2 by effecting displacement of ball `48 from wall 28a when a suflicient rforce is applied to the ball so that it rolls to the flexible contacts 38a, 40a. There the contacts yield as shown by dotted lines in FIG. 3 during the impact of the ball upon them. The external circuit is closed between the circuit conductors 56 and 62 via contact member 60, contact iingers 38a, 40a, the conductive shell 26a, and the metal body lila. It will be understood tha-t the capsule 24 could be substituted for the capsule 24a in body 10a. If capsule 24 is employed in body a then it is possible to effect closing of an external circuit C including three conductors 42, 44 and 56, as indicated schematically in FIG. 7.

FIG. 4 illustrates another form of the invention in which metal body 10b is provided with one or more inclined bores 22a, 22b axially disposed at various acute angles to the registering axes of bore 12a and magnet 14. The capsule 24 or 24a can be inserted in either of the inclined bores in order to provide an lupwardly inclined path -for travel of ball 48 in the capsule. This are rangement in which the ball must travel an upwardly inclined path will require a displacement force of greater magnitude than the arrangements of bodies 10 and lila in which the bore 22 is perpendicular to the bore 12. Bore 22a is disposed at a smaller acute angle to bore 12a than is bore 22b, or stated otherwise, bore 22b is disposed at a lesser inclination to the horizontal than bore 22a. Capsule 24 may be substituted for capsule 24a in body 10b as explained above cEor body 10a. For normal use lthe switches will be operated with the axes of bores 12 and 12a vertical.

The adjustable position off the various contact members in the capsules afforded by means of the threaded plugs 32, 32a provides a further range of control of the switch construction, since the length of time of travel of the ball in .the capsule is determined by the effective length of the path in the capsule. By lengthening or shortening this path there is made possible a range of adjustment of the time interval between displacement of the ball from its seat to its closure of the external circuit.

In assembling the switch, the magnet will be inserted in bore 12 `or 12a. and securely iixed in position by the tightening off plug 16. The selected capsule will then be inserted in one of the threaded bores and locked in position by the associated locking nuts and plugs. The selected plug 32 or 32a will then be adjusted in a desired posi-tion in its support plate or plug and will be secured in position by tightening nut 46. If desired, a threaded member such as plug 50 can also be used as a locking means with the externally threaded capsule 24a as shown in FIG. 4. In general, however, it will be found that the threaded plug 30a provides a suicient pressure to lock the capsule 24a securely in the bore. The various threaded bores are 4all of suiiicient length so that they can accommodate longer capsules having dilierent internal diameters and different path lengths from those illustrated. This effects an economy in manufacture and affords a convenience to the user since the same switch body will accommodate many different sizes of capsules, responding to diierent ranges of externally applied forces. In constructing the switch it is preferred that the ball 48 be the sole magnetic member in the body, excluding, of course, it permanent magnet 14.

FIG. 8 illustrates a `form of the invention similar to FIG. 2. in which corresponding parts are numbered identically. Plug 32 and plate 30 are replaced by a piezoelectric element 70, which may be a circular disk formed of barium titanate or the like. The disk has electrodes 71 and 72 spaced apart on the outer side of the element 70. Conductors 42, `44 are connected to the respective electrodes. When the ball `48 impinges on the element 70 at the end of its travel in shell 26, it deforms the element sufficiently to generate an electrical pulse, which appears across the terminals of conductors 42, 44 and can be applied to an external circuit. The element is retained in bore 22 by the ring or sleeve `52 so that the element 7G can bend at the center when it is struck by the ball.

In the form of the invention shown in FIG. 9, block 10c is a cylindrical body in which cylindrical bore 64 has a smooth wall. Ball 48 is positioned at one end of the bore by a contact 66 secured in an insulated plug 68. The plug has an adjustment slot l79 and fis adjustably positioned in a threaded end 64a of the bore. A similar contact 82 is secured in an insulated plug 74 at the other threaded end 76 of the bore. Plug 74 has an adjustment slot 7S. Since both plugs '68 and 74 are adjustable the length of the path of travel of the ball 48 can be adjusted. The external electric circuit is closed between contact 66 and terminal 55 via ball 48 and body 10c with the ball at one end of the bore. With the ball at the other end of the bore, the circuit is closed between contact 82 and contact 56 via body 10c and ball 48. Magnet 14 provides the restraining force for holding the ball in contact with element 66 at the right end of the bore.

While a limited number of embodiments of the invention have been described, the invention is not to be construed as restricted thereto but is limited only by the scope of the broadest of the appended claims.

What is claimed and desired to protect by Letters Patent of the United States is:

l. An inertia switch, comprising a non-magnetic body, a permanent magnet seated in said body, said body hav* ing at least one bore therein, a hollow non-magnetic capsule removably and adjustably disposed in said bore, means for removably locking said capsule in the bore, a ball of magnetic mate-rial retained at one position in said capsule by `force o-f magnetic attraction to said magnet, said capsule having a path therein adapted for traversing by said ball when displaced Afrom said position by an externally applied force, and at least one electrical contact member disposed in said path for Contact by the ball after displacement from said one position by said externally applied torce, said capsule including a cylindrical shell with closed and open ends and a removable wall member closing the open end of the shell, said contact member being carried by said wall member.

2. An inertia switch, comprising a non-magnetic body, a permanent magnet seated in said body, said body having at leas-t one bore therein, a hollow non-magnetic capsule removably and adjustably disposed in said bore, means `for removably locking said capsule in the bore, a ball of magnetic material retained at one position in said capsule by force of magnetic attraction to said magnet, said capsule having a path therein adapted `for traversing by said ball when displaced from said position by an externally applied force, and at least one electrical contact member Ydisposed in said path for contact by the ball after displacement from said one position by said externally applied force, said capsule including a cylindrical shell with closed and open ends land a removable wall member closing the open end of the shell, said contact member being carried by said Wall member, said bore being internally threaded, said means comprising threads on the said shell and Wall member engaged with the thread of said bore.

3. An inertia switch, comprising a non-magnetic body, a permanent magnet seated in said body, said body having at least one bore therein, a hollow nonrmagnetic capsule removably and adjustably disposed in said bore, means for removably locking said capsule in the bore, a

ball of magnetic material retained at one position in said capsule by force of magnetic attraction to said magnet, said capsule having a path therein adapted for traversing by said ball when displaced from said position by an externally applied force, `and at least one electrical contact member disposed in said path for contact by the ball after `displacement from said one position by said externally applied force, said capsule including a cylindrical shell with closed and open ends and a removable Wall member closing the open end of the shell, said contact member being carried by said wall member, said bore being internally threaded, said means -comprising two threaded members disposed at opposite ends of the capsule :and engaged with the thread of said bore.

4. An inertia switch, comprising a non-magnetic body, a permanent magnet seated in said body, said body having lat least one bore therein, a hollow non-magnetic capsule removably and adjustably disposed in said bore, means `for removably locking said capsule in the bore, a ball of magnetic material retained at one position in said capsule by `force of magnetic attraction to said magnet, said capsule having a path therein ladapted for traversing by said ball lwhen displaced from said position by an externally applied force, and at least one electrical contact member `disposed in said path lfor contact by the ball after displacement from said one position by said externally applied force, there being means adjustably supporting said contact member for adjusting the length of said path between said one position and said contact member.

5. An inertia switch, comprising a non-magnetic body, a permanent magnet seated in said body, said body having at least one bore therein, a hollow non-magnetic capsule removably and adjustably disposed in said bore, means for removably locking said capsule in the bore, a ball of magnetic material retained at one position in said c-apsu-le by force of magnetic attraction to said magnet, said capsule having a path therein adapted for traversing by said ball when displaced from said position by an externally applied force, and at least one electrical contact member disposed in said path for contact by the ball latter displacement from said one position by said externally applied force, said magnet being cylindrical in form, said bore being axially disposed at an angle to the axis of the cylindrical magnet.

6. As an article of manufacture, an inertia switch member comprising fa hollow non-magnetic capsule, a ball of magnetic material disposed in the capsule, said capsule having a path therein adapted for traversing by said ball when displaced from one end of said path by an externally applied tforce, and an electrical cont-act member disposed at the other end of said path for contact by the ball after displacement from said one end by said externally applied force, said capsule including a cylindrical shell with closed and open ends, a wall member closing the open end of the shell and a plug adjustably mounted in said wall member, said contact member being carried by said plug, said contact member including two Iangullarly extending spring `iingers.

References Cited in the le of this patent UNITED STATES PATENTS 1,662,979 Nelson Mar. 20, 1928 2,744,976 Black May 8, 1956 2,802,917 Odegaard Aug. 13, 1957 2,890,303 Clurman June 9, 1959 2,921,999 Ziegler Ian. 19, 1960 FOREIGN PATENTS 120,324 Australia Aug. 24, 1945 

